Implementing a national routine genetic evaluation for milk fat compositions as first step towards genomic predictions

Abstract

Currently the Walloon Region of Belgium is one of the first regions in the World where mid-infra red (MIR) spectral data is recorded in routine for nearly all cows under milk recording. Based on this data, in some herds collected since 2007, saturated (SFA) and monounsaturated fatty acid (MUFA) contents in milk are predicted for each test-day. Together with correlated traits as milk, fat and protein yields, estimated breeding values (EBV) are now computed in routine for SFA and MUFA starting in June 2012. A total of 499 821, 392 255, 277 465 fatty acid records were available in first, second and third lactation for this run. A restricted selection index, called NQI (nutritional quality index) was developed that puts a negative weight on SFA, a positive weight on MUFA and restricts changes in milk and fat yields to zero. By using this index for a constant fat content, milk fat will be selected to be less saturated with a high contribution from MUFA. Based on this system a single-step genomic evaluation is under development including the introduction of MACE breeding values for correlated traits. The final step is to offer for owners of genotyped animals, a service to provide them with genomically enhanced NQI. Similar systems are under development in Wallonia for other novel traits (e.g., methane emissions) based on the ability to predict them from MIR spectral data.